Richard Hamel was watching the 2010 animated film How to Train Your Dragon with his grandchildren when he noticed something odd about the tails of the flying beasts. Hamel, a longtime radio-control plane builder, realized that those appendages resembled an unconventional aircraft design feature known as an inverted V-tail. In lieu of a vertical stabilizer and horizontal rudder, some aircraft rely on two fins arranged in a V shape. “I thought, ‘That would actually work,’” he recalls, "and I started wondering if I could make a dragon fly.”